Sure. And thematically speaking, I feel like if any crew should be getting benefits from corpse markers, it should probably be the Mortuary keyword. Can’t speak to the balance of these other crews. Maybe they need it? Superficial glance says that if they need it yet can’t generate corpses, it becomes a very swingy ability. Great in the matches with plentiful corpses. Bad in matches without them.
Just for fun, looking at the “Loot Their Corpses” ability, all it would take would be a simple change in name have it fit in thematically with Ressers. Could call it “Grisly Harvest” or something, and the fact that the ability removes the corpse marker makes even more sense. I’m not necessarily suggesting this change, but it’s just a thing I noticed.

Perhaps this should be its own topic, but I’ve noticed an awful lot of corpse marker hate in the game now. Some crews from other factions arguably benefit from corpse markers even more than Resser crews. Yet since they lack innate corpse marker production, this benefit comes as a cherry on top of the sundae of things they already do.
For instance, most models in Dashel’s crew freely convert corpse markers to soulstones when they activate. Nephilim get to eat corpse markers to grow into larger nephilim. To say nothing of the decent number of models that don’t drop corpse markers (pigs, constructs, and ghosts come to mind).
I’m already hesitant of bringing a crew that needs (and produces) corpse markers for fear of helping my opponent more than me. From a competitive point of view, it’s safer just to take a less risky choice of crew that works well no matter what.

So, all event organizers maining a single master sounds like an odd situation, but I don't think special treatment is warranted for that. Doesn't sound healthy for the game long term to begin with and it would not set a great precedent.
However, I also hate Reva's new pyre mechanics. I liked the M2E playstyle, and feel this new thing was tacked on thematically. Like hey, we have some fire models in the faction we don't know what to do with, let's just pick a master to give them and build the master around those models. I haven't dug too deep, but nothing comes to mind mythologically about revenants or draugr having any interaction with fire. So I'd be all on board with making Revenants mechanically fit with an "undead" theme rather "fire".
(Also a little jelly of witchhunters who mainly seem to get hard-to-wound without paying the defense tax that Ressers have to pay. As an aside, it's a little thematically disappointing there's no mechanical upside to being undead in this edition.)

Hey, thanks for the report. This one thing stood out to me though. It sounds like this is referring to the aura of healing the Seishin have (Spiritual Healing) because there were 3 of them. If that’s the case, then this may have been played wrong, as auras with the same name don’t stack anymore. Ex: Misery aura in a Pandora crew.

Anyone getting work done with these? They haven’t seemed good enough for me feel good about including them in any lists.
I’m not sure what their role is supposed to be. Df 4 and hard to wound doesn’t seem that survivable. Melee attack isn’t anything special and the triggers seem poor. Ranged attack inflicts damage to self (very bad). Yet they’re also not particularly quick. And they don’t even have a bonus action to use like many other models of their cost.
They just seem below average at almost everything. There’s also a lot of anti-corpse marker abilities among all factions now, so it’s been a real challenge to make use of their abilities that use those as well.